1. Field of This Invention
This invention relates to processes for the analysis of residual gentian violet in tissue, eggs, manure or feed.
2. Prior Art
U.S. Pat. No. 3,915,637 involves a process for the analysis of the residual gentian violet in feed, tissue, eggs or manure. The process includes extracting substantially all of the fat in the feed, tissue, eggs or manure using a fat solvent. (The extraction is preferably done at room temperature. The fat solvent is separated from the feed, tissue, eggs or manure, preferably, by means of centrifuging.) The fat-extracted feed or manure is dried. A known amount of acidified ethanol is admixed with the fat-extracted feed, eggs, tissue or manure, and the resultant admixture is left standing (preferably for 48 hours). The acidified alcohol is separated from the resultant admixture. The amount of gentian violet in the acidified alcohol is determined by spectrophotometrical comparison with acidified alcohol standards containing set amounts of gentian violet.
The extraction, separation and determination steps are repeated until no gentian violet is found to be present in the acidified alcohol, the total of the gentian violet found from the determination steps being the total amount of gentian violet present in the feed, eggs, tissue or manure.
Preferably the fat extraction step involves first extracting the fat from the manure, tissue, eggs or feed at least once with hexane. The preferred fat solvent is petroleum ether, when a one-step extraction process is used, and is the use of petroleum ether, in the first step and the use of hexane in the second step, when a two-step extraction step is used. Other fat solvents can be used. Preferably the acidified alcohol contains 1 ml. of concentrated HCl per 100 ml. of ethanol. Other acids such as concentrated sulfuric acid and concentrated nitric acid can be used in place of the concentrated HCl. Other suitable solvents can be used in place of the acidified alcohol. The determinations can be made by any conventional method, but preferably are made using a spectrophotometer, such as, a Turner spectrophotometer.
The patent also involves a process for checking the accuracy of a process for the analysis of residual gentian violet in feed or manure of animal or poultry.